Many attempts have been made in the past to eliminate the dangers and other shortcomings of metallic cutting heads on the lowermost ends of the vertically disposed drive-shafts of rotary power mowers, the same being most frequently in the form of a transversely-extending rotatable metal bar which is sharpened adjacent its outer ends. The hazardous conditions created by such metallic cutting heads, be they in the form of metallic bars or otherwise, are very well-known, including the dangerous outward propelling by said heads of solid objects of various kinds.
Most of the past attempts to eliminate these hazardous conditions, which are caused by the use of metallic cutting heads of the type referred to, have been the adoption of flexible flails which possess sufficient resiliency to eliminate the outward propelling of solid objects which are contacted at high speeds; but it has been definitely established that mere resiliency is not sufficient to completely overcome the hazardous conditions during rotation of the flexible flails at the necessary high cutting speeds. In addition, the flexible flails of the prior art are usually not provided with easy and inexpensive means for ready replacement of worn flails as caused by frictional contact with the grass or other vegetation. Further, most, if not practically all, of the prior art devices which utilize flexible cutting flails are in the form of hand-carried trimming devices that utilize relatively short lengths of flexible cutting line as paid-out, or dispensed from, a spool and can operate upon only a very small cutting site preparatory to the movement of the device onto a new and uncut or untrimmed area.